Auto-Run disabled? should i be concerned with this error?
This is a feature of Blender that tries to prevent you from running (possibly) malicious code when opening a file.

Animation drivers are actually Python statements (if I recall correctly, there is a way to make them multiline), which normally serve to control l parameters in some advanced ways; rigs tend to have a few drivers, since it's just easier to make work properly that way. However, if someone wanted to, they could, for instance, delete all your files, capture and send private information like passwords, keys and tokens, possibly, without you even noticing. 

If you open the file from within Blender, there is an option to mark a file as trusted and thus run all scripts inside. Use at your own risk.

Another option is, in the User Preferences (CtrlAltU), to allow scripts, from all files, to run; if you don't save the user preferences, they'll only apply to the open file. You can also exclude some directories, if you want; if you do this, I recommend disabling it for your  "Downloads" folder. Again, use at your own risk :P